title: Adipocytic cells augment the support of primitive hematopoietic cells in vitro but have no effect in the bone marrow niche under homeostatic conditions.
abstract: Mesenchymal stem cells (MSCs), as well as osteoblastic cells derived from these MSCs, have been shown to be key components of the hematopoietic stem cell (HSC) niche. In this study, we wished to examine whether other cell types that are known to differentiate from MSCs similarly regulate the stem cell niche, namely cells of the adipocyte lineage. Recent studies have examined the role that adipocytes play in the biology of the HSCs in different bone locations and in transplantation settings; however, none have examined their role under homeostatic conditions. We compared the ability of adipocytic and nonadipocytic cell lines to support primitive hematopoietic cells in vitro. Preadipocytic cell lines demonstrated enhanced support of hematopoietic cells. Similarly, primary bone marrow (BM) cells treated with troglitazone, a drug that enhances adipogenesis, also demonstrated augmented support over control-treated stromal cells. We further examined the effects of increased adipocyte number in vivo under homeostatic conditions using troglitazone treatment and found that these alterations had no effect on HSC frequency. Taken together, we demonstrate that cells of the adipocyte lineage promote the ability of stromal cells to support primitive hematopoietic cells in vitro, yet alterations of adipocyte number and volume in vivo have no effect. These data suggest that adipocytes are not a component of the adult BM HSC niche under homeostatic conditions.
authors.affiliation: Eli and Edythe Broad Center for Regenerative Medicine and Stem Cell Research at USC, Keck School of Medicine, University of Southern California , Los Angeles, California.
authors.forename: Tassja J
authors.initials: TJ
authors.lastname: Spindler
authors.forename: Alan W
authors.initials: AW
authors.lastname: Tseng
authors.forename: Xiaoying
authors.initials: X
authors.lastname: Zhou
authors.forename: Gregor B
authors.initials: GB
authors.lastname: Adams
mesh_terms: D017667:Adipocytes / Q000502:physiology*; D000818:Animals; D001853:Bone Marrow / Q000502:physiology; D001854:Bone Marrow Cells / Q000502:physiology; D016026:Bone Marrow Transplantation; D002450:Cell Communication; D002454:Cell Differentiation; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D002839:Chromans / Q000494:pharmacology; D018920:Coculture Techniques; D006412:Hematopoietic Stem Cells / Q000502:physiology*; D006706:Homeostasis; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D061251:Primary Cell Culture; D055153:Stem Cell Niche; D017154:Stromal Cells / Q000502:physiology; D045162:Thiazolidinediones / Q000494:pharmacology; D000077288:Troglitazone
chemical_list: D002839:Chromans; D045162:Thiazolidinediones; D000077288:Troglitazone